According to a recent study published in the “Journal of Orthopaedic Surgery and Research” Hybrid assistive limb training after TKA was found to be a safe and effective rehabilitation intervention as it showed earlier recovery in patients with no adverse effects.

Total knee arthroplasty (TKA) is the surgery recommended for OA and RA patients. Physical function and quality of life (QOL) is reported to be decreased immediately after the TKA. The results of previous studies suggest that the rehabilitation period of about one year is required for proper walking speed and walking ability. Moreover, after surgery, the knee extension gap may take place early and that is why walking function is particularly important for patients after TKA.

The Hybrid Assistive Limb (HAL) is a wearable robot which on receiving wearer’s consent, aids in movement. Various exoskeleton devices are available in the market that help in generating predefined movement but HAL generates movement only after wearer’s voluntary drive. Muscle activity is adjusted by the wearer to operate HAL. Various clinical trials have been conducted and confirmed the safety of HAL for patients with stroke, spinal cord injury, cerebral palsy, and neuromuscular diseases. Tanaka et al. conducted RCT to compare the efficacy of HAL and conventional therapy after TKA on the lower limb function. The improvement was observed within 1 week with the use of HAL. The study was conducted for a short-term evaluation (3 weeks) after surgery and did not measure the improvement in range of motion (ROM). Moreover, in this study, the two-legged HAL was used and includes only OA patients. Therefore, the present study ascertained and compared the effect of single leg version of HAL on knee ROM, pain, muscle strength, physical function and walking ability with the conventional therapy for up to 8 weeks after TKA for OA and RA patients.

None of the patients in the HAL group has reported any serious adverse events. In the HAL group, a significant improvement in the speed of walking and step length in the self-selected walking speed condition was observed at week 4 and 8. At 2, 4 and 8 weeks, the HAL group shows greater step length in the maximum walking speed condition than in the control group (P < 0.05). At 2 weeks, the HAL group lowered the extension lag and knee pain (P < 0.05) and also significantly raised the muscle strength of knee extension at 8 weeks (P < 0.05).